The use of air conditioning worldwide is still on the increase. It is almost a standard requirement in some workplaces and retail environments and of course in hotter climates the demand on a domestic level is huge. But air conditioning is an energy-intensive technology, and in some countries such as Qatar it is believed that air conditioning accounts for up to 65% of household electricity demand during the hotter months. This kind of demand is a struggle in countries where the power grid is less developed, and across the globe where aging power grids are also commonplace, it is no longer enough to simply work on developing ways to reduce grid-based power consumption. A great way to reduce the demand on fossil fuels and remove the peaks in electricity requirements is thermal solar air conditioning; a natural next step in developing solar technology.
Only a few solar air conditioning systems have so far been developed, and nothing on a mass commercial scale, but there are positive advantages. Solar heat is directly converted for cooling, drying or heating purposes rather than being converted into electricity, so supply and demand can be easily managed, and this fits the 100% utilisation that makes most renewable energies so efficient and desirable. But while there is a growing interest in solar air conditioning, there are currently no political incentives introduced by either UK or US Governments, who otherwise have supported and financed initiatives in solar energy. However, there is a global focus on energy efficiency and ‘cleaner energy’, and solar air conditioning definitely fits into this, and with interest in air conditioning increasing generally, solar air conditioning is sure to become a bigger issue over the next few years.
One notable system currently being developed is in Australia, where an organisation called the Commonwealth Scientific & Industrial Research Organisation (CSIRO) have developed a large scale solar air conditioning model for use in commercial environments. Costing around $1.2miilion to develop it has been trialled in hotels and shopping centres with great success. It uses concentrating thermal technology to produce heat energy which then powers the air conditioning system. Desiccant drying wheels act as dehumidifiers which remove moisture from the air, and no external air is needed to cool or heat the air inside. Collectors capture solar heat at between 150-200˚C and store it in a tank, this is used to heat the ambient air in winter and powers an indirect evaporative cooler in summer. Results have been impressive; energy efficiency has improved as electricity usage is dramatically reduced, general emission levels are also reduced and roughly 40% less roof space is used for the system, compared to traditional air conditioning infrastructure. While development work is still ongoing, CSIRO are of course looking to extend this worldwide.
This is only one system, however, and hence a global embracing of solar air conditioning remains a long term project. On a smaller scale, there are units available that adopt solar thermal evacuated tubes to generate heat and using conventional air conditioning technology, a chiller provides cool air. An external unit is mounted outside facing the sun, while an internal unit delivers cool or warm air into the room. These are only suitable for small rooms/offices and domestic use, but power savings are said to be up to 50% and like any solar air conditioning system, they are self-sufficient units with very low maintenance costs.
It’s clear that interest in solar air conditioning is definitely on the rise, and it seems inevitable that a commercial breakthrough will make it more widely available. Right now, however, major air conditioning manufacturers such as LG, Daikin and Samsung are still developing technologies that are electricity-efficient, rather than trying to eliminate the need for electricity altogether. Meanwhile, the industry works on green air conditioning initiatives such as noise control, emissions reduction, airflow control and using alternative refrigerants. But watch this space – renewable energies are catching up and solar air conditioning is definitely coming soon.
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